Monarch miscalculation: Has a scientific error about the butterflies persisted for more than 40 years?

A few years ago, Christopher Hamm was reading up on monarch butterflies when he noticed something peculiar. All of the scientific articles that mentioned the number of the insect’s chromosomes—30, it seemed—referenced a 2004 paper, which in turn cited a 1975 paper.

 But when Hamm, then a postdoc at the University of Kansas in Lawrence, did a genetic analysis of his own, he found that his monarchs only had 28 chromosomes, suggesting that an error has pervaded the literature for more than 40 years. Another twist, however, was just around the corner.

Hamm suspected a mistake when he read the original 1975 paper. The authors, biologists N. Nageswara Rao and A. S. Murty at Andhra University in Visakhapatnam, India, had studied what they claimed was an Indian monarch butterfly in their work. But there’s a problem: Monarchs are nearly exclusively a North American species. “It’s implied they just went outside their building and collected some butterflies,” Hamm says. “I immediately thought, ‘Monarch butterflies in India? Really?’”

Sure monarchs are master travelers, with the longest-known seasonal migration of any insect. And it’s not uncommon for a few to get blown off course to Australia, the Philippines, the United Kingdom, and a handful of other places from time to time. But ending up as far away as India seemed like a stretch. Hamm, now a data scientist at Monsanto in Woodland, California, also knew that taxonomists since Carl Linnaeus have struggled to distinguish species in Lepidoptera, the order of insects to which monarchs belong. For example, the monarch (Danaus plexippus) and a similar-looking butterfly known as the common tiger butterfly (D. genutia) were thought to be the same for more than a century until they were reclassified as separate species in 1954. And guess what: D. genutia lives in India.

the same or different butterfly?

christopher hamm study one butterfly  that called monarch butterflies but he discovered  one mistake, the insect chromosome number 30,  it seems  referred to the 1975 document.

 did his own genetic analysis, he found that his monarchs had only 28 chromosomes, suggesting that an error has permeated the literature for over 40 years.

 The authors, of the document of  1875 called N. Nageswara Rao and A. Murty, they studied Indian monarch butterfly but  Carl Linnaeus have struggled to distinguish species in Lepidoptera, the order of insects to which monarchs belong.

For example, the monarch  and a similar-looking butterfly known as the common tiger butterfly  were thought to have been the same for more than a century. And hamm discovered that are different types of monarch butterfly.